Help with plexi-glass

[TINY]

What can I use to cut 7/16 thick piece of plexi-glass, I have a 8ft x 6ft piece of it

[Shopdog]

Sabre saw with a very fine toothed blade. Use masking tape on both sides of the cut, IE: run a length of tape where you want the cut and then make your mark in the center of the tape. Go slow slow is the key and keep the blade as square to the sheet as you can and keep your cut straight as well. One slip and that blade gets cocked the sheet will crack. I remember using a heated wire in high school plastics class to cut plexi. thats been awhile so I really don't remember how it worked.

Searcher

[Hambone Slim]

Wow, that's a thick piece of plexi!

Back in a previous life, I was shop foreman in pop display manufacturing companies in RI. Used to stand in front of the table saw all day ripping plexi. We always used triple chip blades. IIRC, 80T for 1/8", 60T for

3/16", and 40T for 1/4". I think the plexi would melt and gum up the blade if I used an 80T for 1/4". I'm trying to remember back 20 years here. I'd recommend a 40T triple chip blade for 7/16" plexi, but I've never tried to cut plexi that thickness.

Generally speaking, more teeth will give a cleaner cut with less chipping, but will generate more heat and create melting and smearing.

Also, the saw cut plexi edge can be cleaned up on the jointer with no problems. THe edge can then be further smoothed with a scraper, then flame polished with either a propane or a map gas torch. Keep the torch mooving, else the edge will scorch and bubble. The flame polished edge will be even shinier than the surface of either cast or extruded sheet. Also, you get a "fiber-optics" effect, where the edges actually look like they are emitting light.

-- Timothy Juvenal

[Kyle Boatright]

As someone has mentioned, a jigsaw would work, but you really need to support the cut well. In addition, you want that plexi to be warm when you cut it. 80f is OK, but warmer is better. It is much less brittle and crack-prone at the higher temps.

[TINY]

[Shopdog]

It shouldn't but why take any chances, I like the idea of heating it. Maybe use a hairdryer to bring the temp up. Make sure you do keep the sheet supported well. Don't knw if you are using saw horses or a table, bt I would definately not let either side of the sheet hang. Support both your good side and your scrap cut off side.

Searcher

[Phisherman]

You can cut it with ordinary wood cutting tools including circular saw, table saw, band saw, etc. The smell and gas might be an issue without proper ventilation. If you can take it outside and cut with a circular saw, you'll be better off. Still wear a good-fitting dust mask.

[Kyle Boatright]

When I've worked plexiglass (airplane canopies) I heated the shop to 80-100f for several hours before making "big cuts". Far easier to do when it is warm outside. It isn't comfortable to work in 95F, but it beats breaking a thousand dollar canopy.

[Peter Huebner]

I've always used a metal cutting blade in a jig saw, and got the speed of the saw right down so the blade doesn't heat up and start melting the plexi-glass.

-P.

[Robatoy]

I cut similar products all day long. Your advice is sound, because the fewer teeth will eject the waste much more efficiently than an 80-tooth blade. TCG is the ticket, and if it has a negative 5-degree rake, even better.

Jigsaws will likely bind if a fine-toothed blade is used. Get a Bosch blade made for plastics.... even then I don't think it is a good idea.

r

[Robatoy]

Will heat up and bind. You want lots of rake and gullet if you're going to jigsaw. 6 TPI max.

[stoutman]

Give this a try:

[lwasserm]

A tablesaw with a carbide 40 to 60 tooth general purpose blade will do a good job. Be sure to have good ventilation, and as a warning, the "sawdust" will want to stick every where from static electricity. Try a few practice cuts to get the speed/feed rate before you cut the keeper piece.